﻿<!DOCTYPE html>
<html>
<head>
  <title>Multi-Arrow Links</title>
  <!-- Copyright 1998-2021 by Northwoods Software Corporation. -->
  <meta name="description" content="A custom Link geometry that draws arrowheads at the end of each segment of orthogonally routed links." />
  <meta name="viewport" content="width=device-width, initial-scale=1">

  <script src="../release/go.js"></script>
  <script src="../assets/js/goSamples.js"></script>  <!-- this is only for the GoJS Samples framework -->
  <script id="code">
    function init() {
      if (window.goSamples) goSamples();  // init for these samples -- you don't need to call this
      var $ = go.GraphObject.make;

      myDiagram =
        $(go.Diagram, "myDiagramDiv", // the ID of the DIV HTML element
          {
            layout: $(go.ForceDirectedLayout),
            "undoManager.isEnabled": true
          });

      myDiagram.nodeTemplate =
        $(go.Node, go.Panel.Auto,
          { locationSpot: go.Spot.Center },
          $(go.Shape,
            {
              figure: "RoundedRectangle",
              parameter1: 10,
              fill: "orange",  // default fill color
              portId: "",
              fromLinkable: true,
              fromSpot: go.Spot.AllSides,
              toLinkable: true,
              toSpot: go.Spot.AllSides,
              cursor: "pointer"
            },
            new go.Binding("fill", "color")),
          $(go.TextBlock,
            { margin: 10, font: "bold 12pt sans-serif" },
            new go.Binding("text"))
        );

      myDiagram.linkTemplate =
        $(MultiArrowLink,  // subclass of Link, defined below
          {
            relinkableFrom: true,
            relinkableTo: true,
            reshapable: true,
            resegmentable: true
          },
          $(go.Shape,
            { isPanelMain: true },
            new go.Binding("fill", "color"))
          // no arrowhead is defined here -- they are hard-coded in MultiArrowLink.makeGeometry
        );

      // create a few nodes and links
      myDiagram.model = new go.GraphLinksModel([
        { key: 1, text: "one", color: "lightyellow" },
        { key: 2, text: "two", color: "brown" },
        { key: 3, text: "three", color: "green" },
        { key: 4, text: "four", color: "slateblue" },
        { key: 5, text: "five", color: "aquamarine" },
        { key: 6, text: "six", color: "lightgreen" },
        { key: 7, text: "seven" }
      ], [
          { from: 5, to: 6, color: "orange" },
          { from: 1, to: 2, color: "red" },
          { from: 1, to: 3, color: "blue" },
          { from: 1, to: 4, color: "goldenrod" },
          { from: 2, to: 5, color: "fuchsia" },
          { from: 3, to: 5, color: "green" },
          { from: 4, to: 5, color: "black" },
          { from: 6, to: 7 }
        ]);
    }


    // Produce a Geometry that includes an arrowhead at the end of each segment.
    // This only works with orthogonal non-Bezier routing.
    function MultiArrowLink() {
      go.Link.call(this);
      this.routing = go.Link.Orthogonal;
    }
    go.Diagram.inherit(MultiArrowLink, go.Link);

    // produce a Geometry from the Link's route
    MultiArrowLink.prototype.makeGeometry = function() {
      // get the Geometry created by the standard behavior
      var geo = go.Link.prototype.makeGeometry.call(this);
      if (geo.type !== go.Geometry.Path || geo.figures.length === 0) return geo;
      var mainfig = geo.figures.elt(0);  // assume there's just one PathFigure
      var mainsegs = mainfig.segments;

      var arrowLen = 8;  // length for each arrowhead
      var arrowWid = 3;  // actually half-width of each arrowhead
      var fx = mainfig.startX;
      var fy = mainfig.startY;
      for (var i = 0; i < mainsegs.length; i++) {
        var a = mainsegs.elt(i);
        // assume each arrowhead is a simple triangle
        var ax = a.endX;
        var ay = a.endY;
        var bx = ax;
        var by = ay;
        var cx = ax;
        var cy = ay;
        if (fx < ax - arrowLen) {
          bx -= arrowLen; by += arrowWid;
          cx -= arrowLen; cy -= arrowWid;
        } else if (fx > ax + arrowLen) {
          bx += arrowLen; by += arrowWid;
          cx += arrowLen; cy -= arrowWid;
        } else if (fy < ay - arrowLen) {
          bx -= arrowWid; by -= arrowLen;
          cx += arrowWid; cy -= arrowLen;
        } else if (fy > ay + arrowLen) {
          bx -= arrowWid; by += arrowLen;
          cx += arrowWid; cy += arrowLen;
        }
        geo.add(new go.PathFigure(ax, ay, true)
          .add(new go.PathSegment(go.PathSegment.Line, bx, by))
          .add(new go.PathSegment(go.PathSegment.Line, cx, cy).close()));
        fx = ax;
        fy = ay;
      }

      return geo;
    };
  </script>
</head>
<body onload="init()">
<div id="sample">
  <div id="myDiagramDiv" style="border: solid 1px black; width:100%; height:700px; min-width: 200px"></div>
  <p>
  This sample demonstrates customization of the <a>Link</a> <a>Shape</a>'s <a>Geometry</a>.
  </p>
  <p>
  The MultiArrowLink class in this sample inherits from Link and overrides the <a>Link.makeGeometry</a> method
  to add arrowheads at the end of each interior segment, assuming that the route is orthogonal.
  </p>
</div>
</body>
</html>
